1. Field of the Invention
The present invention relates generally to solar cells and, more particularly, to an integrated system and process for the continuous formation of p-n junctions in solar cells in a cost-effective manner and under computer control.
2. The Prior Art
The formation of p-n barrier junctions in the manufacture of solar cells traditionally has represented an expensive and time-consuming process step. Several reasons have existed for this. Solar cells must be produced both with high cell efficiencies and with narrow performance distributions. P-n junctions produced according to the diffusion process more or less have met the above requirements but at the expense of other considerations. The diffusion process requires wet chemistry operations which, in turn, require large-scale waste processing plants. In addition, the diffusion process requires detailed and continuous attention to critical process parameters by skilled operators. Further, the diffusion process is dependent on the quality and uniformity of supplies produced by others. Other known processes have been even less efficient and/or desirable. Semiconductor wafers are also sensitive to handling, particularly wafer scratching frequently occurring when the wafers are transported. Forming p-n junctions in solar cells, therefore, involves difficult complexities.